1. Field of the Invention
The present invention relates to a copolymer which is water-soluble or moderately water-soluble and which may be crosslinked.
The invention also relates to the use of the described copolymer as a rheological modifier in very diverse applications, such as drilling muds, textile printing pies, cosmetics, detergents, various other coating compositions such as paints, and as an antisedimentation and/or suspension agent for mineral or organic materials, in various areas of technology, such as, e.g., plant protection.
2. Description of the Background
Copolymers formed from monomers, one of which has a carboxyl group (or groups), and the second of which does not, are known as copolymers which confer distinct rheological properties on aqueous formulations which increase the viscosity thereof. Thus, Eur. Pat. 0,173,109 describes a copolymer comprised of units of an ethylenically unsaturated carboxylic acid, units of an ethylenically unsaturated ester, and units of a third monomer which is the product of the reaction of a fatty alcohol having 6-22 C atoms with an unsaturated isocyanate.
Eur. Pat. 0,013,836 discloses, although only very generally, a copolymer based on methacrylic acid, an alkyl acrylate having up to 4 C atoms, and an oxyalkylated monomer terminated by a fatty chain having up to 30 C atoms. Eur. Pat. 0,011,806 describes the same type of copolymer wherein the third monomer is an ethylenically unsaturated monomer and is terminated by a fatty chain having up to 20 C atoms. Eur. Pat. 0,248,612 claims a copolymer wherein the third monomer is an ester having a fatty chain containing up to 25 C atoms.
Further, Eur. Pat. 0,216,479 describes, although only very generally, a copolymer based on an ionic ethylenically unsaturated monomer, a substantially nonionic ethylenically unsaturated monomer, an oxyalkylated allyl ether having up to 30 C atoms, and a crosslinking agent.
All of the publications describe polymers which do not perform entirely satisfactorily when employed in certain formulations, however. A need therefore continues to exist for a method of increasing the "apparent viscosity" of aqueous suspensions at low shear gradient to confer excellent stability on aqueous suspensions of mineral or organic materials, particularly antisedimentation stability, without a correspondingly large increase in the viscosity such as is frequently experienced with polymers known to the art.